Radiation and pregnancy

During pregnancy, it is best to avoid medical imaging examinations that use ionising radiation. It is important to protect the unborn child.

This is why healthcare professionals will ask if you are pregnant, or if it is possible that you could be.

Risks for the unborn child

Exposing an unborn child to radiation poses particular risks:

• death of the embryo;
• birth defects;
• intellectual disability.

These risks depend on:

• the stage of pregnancy;
• the dose to which the foetus is exposed.

First 10 days of pregnancy

During the first 10 days after conception, irradiation has an ‘all or nothing’ effect:

• either the death of the embryo;
• or normal development.

At doses of over 100 milligrays, the death of the embryo is sometimes observed, but the embryo can also survive without harm at much higher doses.

Between the first hours and the 10th day after conception, the risk of birth defects or intellectual disability directly linked to exposure can be ruled out.

From the 11th day until the 8th week

From the 11th day until the 8th week after conception, there are risks of birth defects with high doses.

It is accepted that there is a threshold of around 100 milligrays below which there is no risk of birth defects.

These thresholds are most likely to be reached during radiotherapy or interventional radiology treatments, but they can also be reached after certain medical imaging examinations.

Between the 8th and 25th week

Between the 8th and 25th week after conception, while the brain is developing, there is a risk of intellectual disability associated with high doses.

With doses of less than 300 milligrays, the risk of serious intellectual disability can be ruled out. No significant reduction in intelligence quotient (IQ) has been demonstrated for doses below 100 milligrays.

Risks for pregnant women

If you are pregnant and have been exposed to X-rays, the most important thing is not to panic. The risk depends on the dose of radiation.

A single low dose is unlikely to have any effect, but if you have any doubts, talk to your doctor.

For unborn children, critical doses are generally those above 100 milligrays (millisieverts).